Electron gun for cathode-ray tubes



Feb. 3, 1953 w, VAN ORNUM 2,627,585

ELECTRON GUN FOR CATHODE-RAY TUBES Filed Sept. 1, 1950 F/gi WESLEY H.VAN ORNUM INVENTOR.

/-//s ATTORNEY Patented Feb. 3, 1953 UNITED STATES PATENT O FF I CE W se en O e q a a o liarlaeeqcmraiina wreeiaiicec Application eptember 1,1950, Serial No. 182,774 .3 cla ms} (01. ,3::

This invention relates a to electron guns for cathode-ray tubes or thelike, and morepart-icularly to a novel supporting arrangement for theelectrodes constituting an electron gun.

A conventional cathode-ray tube electron gun comprises a plurality oftubular electrodes, including first and second grids and an anode,arranged in predetermined mutually spaced relation to direct and controlan electron beamorigihating at an indirectly heated cathode. It iscustomary practice to provide studs extending outwardly from each of thetubular electrodes at correspondingly spaced peripheral intervals and toaffix rigid insulating spacer-support members to longitudinally alignedstuds in order to support the second grid and the anode from the firstgrid. To this end, the outwardly-extending studs are individually weldedto the respective tubular electrodes; this welding operation is bothtimeconsuming and costly.

It is theobi f e resentinv n t Pr vide a new and improved electron gun,for a cathode-ray tube or the like, in which, th several electrodes aresupported in a desired predetermined mutually-spaced relation in asimple and economical manner.

In accordance with the invention, an electron gun for a cathode-ray tubecomprises first and second tubular electrodes. outwardly-extending studsare supported by the respective first and second electrodes, at leastone of the studs being in the form of an integral projection struck fromone of the electrodes. A rigid insulating spacersupport member isaffixed to the studs to support the two electrodes in predeterminedlongitudinally spaced relation with respect to each other.

The features of the present invention which are believed to be novel areset forth with particularity in the appended claims. The invention,together with further objects and advantages thereof, may best beunderstood, however, by reference to the following description taken inconnection with the accompanying drawing, in the several figures ofwhich like reference numerals indicate like elements, and in which:

Figure 1 is a fragmentary view, partly in section, of a cathode-ray tubecomprising an electron gun constructed in accordance with the presentinvention;

Figure 2 is an elevational View, partly in section and taken in adirection at right angles to the showing of Figure 1, of the electrongun structure; and

Figure 3 is a plan view of one of the electrodes.

As shown in Figure 1, a cathode-ray tube may 2 comprise an evacuatedenvelope l0 having an electron gun-for directing a focussed electronbeam to a fluorescent screen (not shown) provided at one end I. I of theenvelope. The electron gun comprises three tubular electrodes [2, l3 andIt, conventionally designated the first grid, the second grid, and theanode respectively. A conductive coating iii is applied to the innerwall of the envelope Ii! toprovide a field-free path for the electronbeam in its progress from the electron gun to the fluorescent screen,and conductive coating I 5 is maintained ata common potential with anodeM, by

-means of-a plurality of resilient metal contacts 136. As best shown inFigure 2, a thermionic cathode I 1, preferably of the indirectly-heatedtype, is supported within the first grid [2 by means of an insulatingspacer [8.

Each of the electrodes l2, l3 and I4 is provided with a plurality-ofoutwardly-extending studs [9, 2t, and 2! respectively, and a pair ofrigid insulating spacer-support members 22 and 23 are affixed tolongitudinally aligned studs i9, 29 and 2| supported by the severalelectrodes. In this manner, the electrodes are maintained in a desiredpredetermined mutually-spaced relation, the second grid I3 and the anodeIt being supported by the first grid l2 which in turn may be held firmlywithin the evacuated envelope Ill by means of support members 24(Figure 1) extending inwardly from the base of the tube.

In accordance with the invention, some or all of the studs I9, 25], and2| are constructed as integral projections struck from the respectiveelectrodes [2, I3. and It. In order to obtain increased rigidity, it ispreferred that the projections be folded or channeled as indicated inFigure 3. In this manner, the necessity of welding separate stud membersto the electrodes is obviated.

The striking and channeling operations may readily be performed byautomatic equipment by the use of properly cut dies, in order to renderthe fabrication of the electrodes feasible for large scale production.As indicated in Figure 3, a generally rectangular aperture 25 may be cutin the electrode cylinder, 1eaving the material intact at each end ofthe aperture. A cross-cut may be made at an intermediate positionindicated by the dotted line 26, and the two cars thus formed mayreadily be bent up and channeled to form the finished studs 2 I It hasbeen found that the provision of one or more apertures 25 in the tubularelectrodes permits the formation of the desired stud configurationwithout detrimentally afiecting the formation or focussing of theelectron beam. Unclesirable discontinuities in the electrostatic fieldsexisting within the respective electrodes are substantially avoided solong as the total area of the removed material is small relative to thetotal circumferential area of the electrode.

While the illustrated embodiment employs a pair of oppositely disposedrigid insulating spacersupport members 22 and 23, it is, of course,possible and within the scope of the invention to provide three or moreof such spacer-support members; in any event, it is preferred that thestuds extending outwardly from the several electrodes be spaced atsubstantially equal peripheral intervals. In this manner, the rigidityof the composite structure against subsequent deformation in anydirection is optimized,

The particular electron gun structure illustrated in Figures 1 and 2 isof the type in which 'the anode is laterally offset from the first andtrodes are maintained in accurate coaxial alignment.

While a particular embodiment of the present invention has been shownand described, it is apparent that various changes and modifications maybe made, and it is therefore contemplated in the appended claims tocover all such changes and modifications as fall within the true spiritand scope of the invention.

I claim:

1. In an electron gun for a cathode-ray tube: first and second tubularelectrodes; a stud supported by said first electrode and extendingoutwardly therefrom; at least one stud in the form of an integralprojection struck from said second electrode and extending outwardlytherefrom; and a rigid insulating spacer-support member afiixed to saidstuds to support said second electrode in predetermined longitudinallyspaced relation with said first electrode.

2. In an electron gun for a cathode-ray tube: first and second tubularelectrodes; a stud supported by said first electrode and extendingoutwardly therefrom; at least one stud in the form of a channeledintegral projection struck from said second electrode and extendingoutwardly therefrom; and a rigid insulating spacer-support memberaffixed to said studs to support said second electrode in predeterminedlongitudinally spaced relation with said first electrode.

3. In an electron gun for a cathode-ray tube:

" a plurality of tubular electrodes including a first grid, a secondgrid, and an anode; a plurality of studs supported by said first gridand extending outwardly therefrom at substantially equal peripheralintervals a plurality of studs supported by said second grid andextending outwardly therefrom at peripheral intervals correspending tothose of said first-mentioned studs; a plurality of studs in the form ofintegral projections struck from said anode and individually extendingoutwardly therefrom in substantial longitudinal alignment withcorresponding studs supported by said first and second grids; and aplurality of rigid insulating spacer-support members individuallyaflixed to longitudinally aligned studs supported by said first andsecond grids and by said anode.

WESLEY H. VAN ORNUM.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date Re. 22,378 Bowie Sept. 21, 19431,550,768 Weinhart Aug. 25, 1925 2,096,415 Weinhart Oct. 19, 19372,096,466 Painter Oct. 19, 1937 2,129,005 Hudec Sept. 6, 1938 2,163,233Brown June 20, 1939 2,436,264 OLarte et a1 Feb. 17, 1948 2,441,315Forgue May 11, 1948 2,451,323 Foulker Oct. 12, 1948 2,487,592 RishellNov. 8, 1949

